G'huun the Plaguebringer

"I will give your flesh purpose."

The horrible abomination known as G'huun is the progenitor and source of the vile disease Black Vein. G'huun was created by Nex towards the end of The Eclipse War, and burrowed into the Underdark of Crescentia to hide and fester at the beginning of the Second Age. Created as part of Nex's contingency plan should something happen to him during the Eclipse War, G'huun's singular purpose was to spread the vile disease it had been gifted with, as was able to do so with the Silver Elves first as Alathar Balefrost and his people accidentally awakened the monster in the depths of The Silver City.
Responsible for the near extinction of the Silver Elves and the loss of countless lives across Western Arkos due to the spread of Black Vein, G'huun was eventually destroyed and Black Vein cured by The Companions and Dr. Corvo Callous, after they journeyed into the long vacant Silver City and confronted G'huun in its festering nest.